I found a neat item for model RR and other hobby use when recycling something that many of us commonly get, use, and throw away - the humidifier tank from a CPAP machine. CPAPs are used by folks with sleep apnea to keep breathing while they sleep. The humidfier tanks are now commonly conisdered a use items and mine are replaced every 3 months.
Here’s one of my Resmed tanks, a very common brand, and the packaging with part number on it.
It’s mostly plastic, but what I’ve been looking at is the stainless steel bottom. This metal part is mostly enclosed by the tank’s plastic shell, but the bottom is left with metal open to quickly transfer heat from the pad that warms the water.
The metal piece can be pretty easily extracted from the plastic shel with some cutters or rail nippers. Wear gloves while cutting to protect your hands from any sharp plastic edges, but the metal piece is sandwiched in between two parts of the plastic shell and once this is mostly defeated it’ll pop right out.
The metal is shaped in such a way so that there’s a pretty ideal pool for most decals. The sides offer a couple of "lounging areas’ for decals to rest, either wet or not. The edge is raised all along, making it easier to get the needed wet spot to your workbench without sloshing out along the way.
Finally, the rim is shrouded in a silicone bumper, leaving it very safe to use.
The only thing thing it may need is a leg under the side that has the raised platform to keep it from tipping in that direction. As is, the weight and limited volume of the lower tank area tends to resist tipping. Otherwise, a useful find that is common enough you should be able to come up with a tank to recycl